This thesis makes the case for thinking that Mary Midgley is a Neo-Aristotelian Naturalist. I have two central aims. First, I defend a historical and philosophical case for Midgley’s inclusion into the contemporary branch of meta-ethics known as ‘Neo-Aristotelian Naturalism’ – a form of meta-ethical naturalism which seeks to found ethics on claims about human nature. To re-establish Midgley’s historical position within this programme I begin by assessing and debunking the reasons for Midgley’s exclusion from Neo-Aristotelian Naturalism within the historical branch of meta-ethics, and more broadly, Midgley’s neglect from the analytic tradition. I then argue that Midgley ought to be included among those paradigmatic philosophers credited with the development of the sub-division of Neo-Aristotelian Naturalism known in the literature as ‘first nature naturalism’. This involves an essentially historical element in situating Midgley within the early development of this meta-ethical naturalism, alongside Elisabeth Anscombe, Philippa Foot, Alastair MacIntyre, Rosalind Hursthouse, and Peter Geach. Second, I argue that an appeal to Midgley’s naturalism can solve a central issue we find in other formulations of Neo-Aristotelianism. Broadly put, Midgleyan Neo-Aristotelianism collapses the conceptual distinction between human animals and nonhuman animals typically found within the history of ethics and inherited by many formulations of Neo-Aristotelian Naturalism. In doing so, Midgley’s naturalism is able to account for the relevance of facts about a human’s biological nature to their rational nature (a dichotomy which Midgleyan naturalism denies prima facie). Ultimately, the upshot of this thesis is that Mary Midgley is an important in the history of ethics, particularly in the context of discussions about meta-ethical naturalism.